"Is it better to take a drug like Marinol, or is smoking bud just as good?"
Firstly not all cancers kill you. More then 50% of people who have cancer live more then 5 years and some cancers have a survival rate of 90%.
Cancers can spread to different parts of your body and effect the patient differently. For example if the cancer is in the lungs it may take over much of the normal lung and cause a issue with oxygen supply or collapse and cause infection. If the person is already weakened even antibiotics may not help to cure it and the person can die from the infection.
If the cancer is in the liver, which as one of its functions detoxifies the blood, it may not be able to perform this and could lead to chemical imbalances in the body.
The bone marrow is responsible to make blood cells. With cancer in the bone marrow it can cause a decrease in the red blood cells which decrease the amount of oxygen you can carry in your blood. Also it can cause a decrease in the white blood cells which can lead to decrease in your ability to fight infections as well as decrease platelets which can cause abnormal bleeding.
If the cancer is in your digestive system it can physically cause an obstruction preventing you from having the food you eat become digested and absorbed.
With all of this occurring, the cancer itself is growing at a high rate of metabolism and utilizing a lot of the nutrients and energy that the body normally needs as well as cause a decrease in appetite. Some types of treatments, such as chemotherapy, can lead to nausea and vomiting further decreasing the amount of nutrients that are absorbed into the body.
As a result of all this some patients so indeed die from malnutrition, but there are unfortunately other way these people pass away from as well. Cannanbis has been shown to help decrease nausea from chemotherapy and well as stimulate appetite as well.
Perry Solomon, MD